The present invention relates to a recording liquid and, in particular, to a recording liquid suited for use in ink-jet recording.
The ink-jet recording system in which recording is performed by ejecting droplets of a recording liquid containing a water-soluble dye such as direct dye or acid dye from fine discharging orifices is now in practical use.
Recording liquids used in the ink-jet recording system are required to fix fast on recording paper of common office use such as PPC (plain paper copy) paper for electrophotography and fanfold paper (continuous paper for computers), to form high-quality images, in other words, to form clear-cut outlines of ink dots without blotting, and to have excellent storage stability, so the solvents usable for this kind of recording liquid are very limited.
Regarding dyes used for the recording liquid, on the other hand, the dyes are required to have sufficient solubility in the limited usable solvents, to remain stable even when it is stored for a long time in the recording liquid, to provide a high density of recorded image and to have excellent water and light resistance. However, it has been difficult to obtain a dye which can meet all of these requirements.
In an effort for satisfying above requirements, many proposals have been made (Japanese Patent Application Laid-Open (KOKAI) Nos. 61-101574, 61-101576, 61-195176, 61-62562, 61-247771, 62-156168 (USP 4,771,129), 63-63765, 63-295685, 1-123866, 2-16171, 3-122171, 3-203970, 4-15327, 4-279671, etc.). Nevertheless, none of them has yet reached a level which satisfactorily meets to the requirements.
The present inventors have found that when a specific compound as a dye for a recording liquid, there can be obtained a magenta recording liquid which, even when used for ink-jet recording or for recording with ordinary writing instruments on plain paper, is capable of forming a recorded image with high quality, high density and excellent color tone, and which also has excellent water and light resistance and is stable when stored for a long time. The present invention has been attained on the basis of this finding.